The present invention relates to a disc brake arrangement for vehicles and, more specifically, to a disc brake arrangement including a disc rotatable with a wheel, a caliper having a bridge portion disposed across the disc, a pair of friction pads disposed on both sides of the disc in such a manner that they are movable along the axis of the disc, means provided on the caliper for engaging the pads with the disc and a pad spring for retaining the pads in place under load.
As is well-known in the art, the disc brake arrangements of the floating caliper type or the opposed piston type are provided with a pad spring adapted to prevent vibration and rattling of friction pads which engage with a disc for braking. The pad spring is formed of a single elastic plate, and interposed between the upper portions of the pads and the inner wall of the bridge portion of the caliper.
With the floating caliper type brake, however, the point of pad-engagement of the pad spring on the reaction force side remains intact, but the point of pad-engagement of the pad spring on the operable side shifts with the resulting increase in load, as the friction pads wear away.
Consequently, difficulties are encountered in maintaining a load preset by the pad spring, so that the friction pads are out of balance, leading to a tilt, local wearing or dragging thereof.
With the opposed piston type brake, on the other hand, there may be a non-uniform change in the amount of movement of both friction pads. That change also causes the pads to be out of balance, thus offering such problems as mentioned above.
Furthermore, the pad spring should be located and temporarily held in place to permit simple and easy assembling thereof.
A misalignment problem arises particularly with a pad spring whose pad engaging portions are different in shape on the operable and reaction force sides.
With a disc brake including a caliper formed by casting, the inside face of the reaction force portion to be in abutting contact with the rear plates of friction pads is mechanically finished, while the central inner wall of the bridge portion for supporting a pad spring is as-cast. For this reason, a difficulty is encountered in arranging the said inside face at a right angle with the said central inner wall, so that a load preset by the pad spring becomes unstable. This causes a tilt, local wearing and dragging of the friction pads.
With another pad spring including pad-engaging portions which are separately formed on the operable and reaction force sides, extra work is required since friction pads have to be associated and located appropriately with the respective pad-engaging portions.